Answer:
x = -5
y = 6
Step-by-step explanation:
3x + 7y = 27 --------------(I)
-3x + y = 21 -----------(II)
Add equation (I) & (II) and so x will be eliminated and we can find the value of y.
(I) 3x + 7y = 27
(II) <u> -3x + y = 21 </u> {add}
8y = 48
y = 48/8
y = 6
Plugin y = 6 in equation (I)
3x +7*6 = 27
3x + 42 = 27
3x = 27 - 42
3x = -15
x = -15/3
x = -5
Answer:
63
Step-by-step explanation:
Because, 100% of 70 would be 7. Now we have that number lets multiply it by 9 because of 90%. 9 x 7 = 63 first-graders
Finished:Left
8:1
8/1 = 72/x
Cross Multiply
8x=72
divide each side by 8
x=9
She already finished 72 and has 9 remaining
Total = Finished + Remaining = 72 + 9 = 81