# If y is directly proportional to x and z and inversely proportional to w, and y = 4 when x = 2.5 and z = 2 and w=1, find y when x = 4 and z =1 and w=2.

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y is directly proportional to x and z and inversely proportional to w, and y = 4 when x = 2.5 and z = 2 and w=1.

Let y = k1*x and y = k2*z and y = k3/w

As y = 4 when x = 2.5 and z = 2 and w=1

4 = k1*2.5

=> k1 = 4/2.5 = 1.6

4 = k2*2

=> k2 = 2

4 = k3/1

=> k3 = 4

**When x = 4, y = 6.4, when z = 1, y = 2 and when w = 2, y = 2**