Tell me please very much it is necessary maty 427,428 I beg you very much the help is necessary

40
7/12+7/20= on 12 and on 20 shares 60 60:12=5 60:20=3 Now we multiply 7/12 by 5 7 to increase by 5 = 35 12 to increase by 5 = 60 we multiply 7 by 3 = 21 20 to increase by 3 = 60 it turns out 35/60 + 21/60 = 21+35 = 56/60
3
Answer add