A+b = 30 a: b is equivalent to 2: 3. what is a& b

One way is to use brute force (find bigger equivilent ratios and add them)
2:3

to make them bigger, we multiply both by the same number
2:3
2+3=5 nope

2:3 times 2 to both=4:6
add
4+6=10
we can just add the numbers before multiplying and then multiply after

2+3=5
5 times what=30
divide both sides by 5
6=what
we need to multiply each by 6
2:3 times 6 to both =12:18
12+18=30

a=12
b=18