math

Is it the last option? 40

x-50=41, x=91, x-50=59, x=109. So, (D). 

Mary travels (at a minimum)    4 * 40  = 160 miles

And at a maximum of  4 * 60  = 240  miles

So....she travels between  160  and 240 miles

But...since she drives 50 miles less than Marty, Marty must travel  between 160 + 50  = 210 miles and 240 + 50  = 290 miles

So...the second choice is correct.....