15+17\dfrac{1}{5} + \dfrac{1}{7}
15+17\dfrac{1}{5} + \dfrac{1}{7}
Since these fractions have different denominators, we need to find the least common multiple of the denominators
The least common multiple of 5 and 7 is 35, so we need to multiply to make each of the denominators = 35
15∗77=735\dfrac{1}{5} * \dfrac{7}{7} = \dfrac{7}{35}
17∗55=535\dfrac{1}{7} * \dfrac{5}{5} = \dfrac{5}{35}
Since these fractions have the same denominator, we can just add the numerators
735+535=1235\dfrac{7}{35} + \dfrac{5}{35} = \dfrac{12}{35}