A=xy If there is 10% increase in x then, New value of x = x + 10%of x =1.1x similarly for y New value of y after increase= 1.1 y New value of A after increase in x and y = 1 .1x × 1.1 y= 1.21xy now increase amount in A= New value of A - old value of A =1.21xy - xy= 0.21xy percentage increase in A= (0.21xy÷xy )× 100= 21%
