Wanda and Claire each open new bank accounts at time $0.$

Wanda deposits $1,000$ into her bank account, and Claire deposits $700$ into hers. Each

account earns the same annual effective interest rate, $/.$

The amount of interest earned in Wanda's account during the $11$th year is equal to X$.$ The

amount of interest earned in Claire's account during the $15$th year is also equal to X$.$

Calculate X$.$