School Supplies Ltd sold 40 000 text books in January and 12 000 in July. Shipping costs for these two months were $150 000 and $80 000 respectively. Using this data, the shipping cost function is best estimated as:

Select one:

1.

$50 000 + $2.50 x

2.

$70 000 + $2.50 x

3.

$50 000 + $3.75 x

4.

$70 000 + $3.75 x