The answer would be X =90
Well I don't know !
Let's check out the choices:
A). 3a - 4b = 21, a=0, b=7
3(0) - 4(7) = 21
0 - 28 = 21 Nope. That's not true.
B). 3a - 4b = 21, a=-3, b=2
3(-3) - 4(-2) = 21
-9 + 8 = 21
-1 = 21 Nope. That's not right.
C). 3a - 4b = 21, a=-2, b=-3
3(-2) - 4(-3) = 21
-6 + 12 = 21
6 = 21 Nope. That's not it.
Only one choice left.
This one had better be it:
D). 3a - 4b = 21, a=7, b=0
3(7) - 4(0) = 21
21 - 0 = 21
21 = 21 Yay ! That's it !
The answer is 60 ft
You do L × W ×H
which is 3 × 4 × 5 = 60
-3^6 = -729
-729 +(-4+7)(2)
-729 +(3)(2)
-729 + 6
-723
<em>hope it helps :)</em>
(ps: the result of -3^6 is not +729, the expression that would give this result is (-3)^6
