Answer:
10
Step-by-step explanation:
x:14=15:21
14/21 = 2/3
Multiply each term by 2/3
15 *2/3 :21*2/3
10:14
The missing number is 10
15 = 5x + 45
15 - 45 = 5x
-30 = 5x
-30/5 = x
-6 = x
18
I hope this helps
−5(z+1)=−2z+10
one solution
1) 3x=7-y
X=7-y/3
2) 4x=16-y
X=16-y/4
