Question

x is partly constant and partly varies with y. When y=3, x = 7 and when y = 6, x = 9. Find x when y = 4

Answer 1

x=23/3

Explanation:

x=c+ay

7=c+3a | *(-1)

9=c+6a

-7=-c-3a

9=c+6a

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9-7=c-c+6a-3a

2=3a

a=2/3

7=c+3*2/3

7=c+2

-2 -2

5=c

so x=5+2/3*y

when y=4 then x=5+2/3*4=5+8/3

x=15/3+8/3

x=23/3