Question

a/4+a/3=21

Answer 1

find a common denominator for your 'a's. In this case, we just multiply each number the the denominator of the other. (3/3 * a/4) + (4/4 * a/3) = 21
now we add then, and get 7a/12 = 21
multiply by 12, divide by 7.
you get a = 36

Answer 2

Firstly, what is the lowest common multiple of 4 and 3? It is 12.

Convert both fractions to something over 12 by multiplying by 3 and 4 respectively.

So (3a/12) + (4a/12) = 21.

This gives 7a/12 = 21

This can be simplified to get 7a = 252 and a = 252/7 = 36.

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Answer 3

a/4a+a/3=21
a/4+a/3=7a/12
7a/12=21
mek a
7a=21x12
7a=252
a=252/7
a=36