Note :- need calculation

Susan manufactures robots for the farming industry. She makes 2 farming robot models, TM1 and TM2, which are primarily programmed to pick up eggs. Susan wanted to generate some publicity for her business, so on Thursday, she put an advert in the Farm News, a news publication circulated widely amongst farmer in the area. The advertisement was intended for the TM1 robot and stated as follows: 'Special offer: One technologically advanced TM1 robot will be sold to the first person who comes to my factory on Monday and makes an offer of $50,000 for it written on an egg-shell'. Carl runs a free-range egg farm and needed a new robot to collect eggs. On Friday, he emailed Susan an offer of $60,000 for TM1. He stated that he needed it to replace his broken robot. Susan immediately accepted Carl's offer and sent the TM1 robot to him straight away. On the following Monday morning, Razwana was the first person to attend Susan's factory. She presented her offer of $50,000 written on an egg-shell. However, Susan told Razwana that her offer was too late since the TM1 robot had already been sold to Carl. Later that week, Jacob made an enquiry about the TM2 robot. Susan replied, quoting a price of $80,000, subject to her standard terms and conditions. These included a price variation clause, providing for a price increase if the cost of metal components went up before delivery. Jacob replied, using his own order form for the TM2 robot, confirming the purchased price at $80,000. However, it contained different terms and conditions, with no price-variation clause. It had a tear-off slip for accepting the terms of the order. Susan signed the tear-off slip and returned it to Jacob. Susan delivered the TM2 robot to Jacob 2 weeks later as agreed and also enclosed an invoice for $90,000 for the TM2 robot, to reflect increases in the cost of metal components, but Jacob is refusing to pay more than $80,000. Answer the following questions based on the above facts. (a) Is Susan in breach of contract with Razwana? (b) Is Jacob contractually bound to pay $90,000 for the TM2 robot? [You must justify your answer using case law]