Please explain the problem in the attachment. I'm not seeing the math. Thank you.
I got D.
First glance it is A for me, but after working on it, it turns D.
a = Last year price for model A
b = last year price for model B
This year price for model A = 1.15a
This year price for model B = 0.75b
Want to know if:
1.15a > 0.75b ?
(1) b = 1.1a, plug this in the equation, you get
1.15a > 0.75*1.1a
This is always true. SUFFICIENT.
(2) a = b + 10
Plug this back in, you get
1.15*(b+10) > 0.75b
1.15b + 11.5 > 0.75b
This is always true as well.