to solve it, you need to find the greatest common denominator. so 10 and 45 are both factors of 90. so then you have to multiplying the denominator and numerators of both fractions to make them both of 90.
4/45 (multiply the denominator by 2 to get 90, and what you do the bottom you have to do to the top, so 4×2)
4/45 = 8/90
7/10 = 63/90
then just add the two fractions together. 8/90+63/90=71/90
so the answer is 71/90
Hope this helped!!
