Explanation:
No . 7
y = K X ( this ithe equation ,need to find K )
12 = k × 1/3
k=12 x 3 = 36
y= 36 X → ( equation
No . 8)... the same Way
k = 21 / 14= 3 / 2
y= 3/2 X
NO . 9
X 1/ X 2 = y1 / y 2
4 /10 = -10 / y 2
y2 = -25
No. 10
x 1 / X2 = y1 / y 2
.48 / X2 = 36 / 18X
X2 = 24