Question

can any one tell me how it came 9d please dear answer i have test tomorrow ​

Answer 1

we have take lcm in the place where d/50+d/40

then we get correct answer attimatically

Answer 2

it's simple since d/50 cannot be added by d/40 unless the denominator are same so we need to find lcm and so it is 200 for 50 and 40 thus when we change the denominator of 50 and 40 we even multiply the numerator with the same number used to mutiply fifty and forty thus the numerator are five and four which when added is nine by 200