Question

find the value of a and b

Answer 1

This is an integer problem.

Answers : 
   a = 5. and   b = 1

See the solution.

$4\frac{1}{a} \times b \frac{2}{3}=7\\\\\frac{4a+1}{a} \times \frac{3b+2}{3}=7\\\\(4a+1) \times (3b+2) = 21*a.$

From the above : 
    3b+2 cannot be equal to 21 or 3 or 7.   (3b+2 can be 5 or 8).
    4a + 1 can be = 21 ...    So a = 5.

    3b + 2 = a = 5
     So   b = 1.