hi
Golden rule : you can only add or substract fraction if and only if they have the same denominator.
so two solutions :
you see that one denominator is a multiple of the second. so you multiply all the fraction by this multiple.
ex : 1/3 + 5/6
here I can easely convert 1/3 into a fraction with 6 as 6 is 3x2.
so : 1x2 = 2 and 3x2 = 6
1/3 is 2/6
so. 1/3 +5/6 = 2/6 +5/6
fraction have same denominator, I add numerators : 2/6 +5/6 =7/6
if it not that evident, you multiply fraction A up and down by denominator of fraction B.
and you multiply up and down fraction B by denomonator of fraction A
let' s see with your exemle :
3/4 +4/7+3/4 = ?
first I add fraction with same denominator :
3/4+3/4+4/7 = 6/4 +4/7
fraction A is 6/4.
I multiply up and down by denominator fractiok B which is " 7"
so. 6/4 = 6x7/4×7 = 42/28
let's apply method to fraction B whixh is 4/7 . let' multiply up and down by denominator of fraction A which is " 4"
so : 4/7 = 4x4 /7x4 = 16/28
now we have :
6/4 +4/7 = 42/28 +16/28
both my fractions have same denominator "28" so I add numerator :
42/28 +16/28 = 58/28
Now must wonder if 58/28 can be simplify. Good trick is to decompose numbers, and in prime number is the best way to do
58 = 2x29
28 = 7x2x2
so 58/28= (2×29)/ (7x2x2)
when there is same number up and down I can cross it out .
so here one "2" up and down can be rule out
so 58/28 = 2x29 /7×2×2 = 29/7x2 =29/14
I can not symplify more, so calculus is over.
in short :
3/4+4/7+3/4 = 6/4+4/7
= 42/28 +16/28
=58/28
= 29/14