A company divided a bonus among its employees A, B, and C in the ratio 2 : 3 : 7. C's bonus was X% more than the combined bonus of A and B. Find X.

1. Find the ratio parts for the combined bonus of A and B and for C

A : B : C $=2:3:7$

Combined bonus of A and B $=2+3=5$ parts.

C's bonus $=7$ parts.

2. Find how much more C received than A and B combined

Excess of C's bonus over the combined bonus of A and B

$=7-5=2$ parts.

3. Express the excess as a percentage of the combined bonus of A and B

$X=\dfrac{2}{5}\times 100\%$

$=40\%$