Question

Find the value of x in the given ratio 2x/21=12/18

Answer 1

2x/21=12/18
Use cross multiply
2x(18)=21×12
36x=252
Divided 36 for both side
36x/36=252/36
x=7. As a result, x=7 is your final answer. Hope it help!

Answer 2

You can use something called crossed multiplication (not sure the official name but something like that) basically when you have 2 fractions that equal to each other, you can multiply the numerator on the left-hand side with the denominator on the friction on the right side. and repeat the same with the numerator on the right side and multiply it by the denominator on the left. that way, there will be no more fractions and will just leave you simple algebraic equations.
so in here$2x / 21 = 12 / 18 252 = 36x x = 7$