if the sum of the 6th and 7th terms of an arithmetic progression is 60 and the 3rd term is -5 find the common difference

Answer 1

"the sum of the 6th and 7th terms of an arithmetic progression is 60" --> a+5d + a+6d = 60
2a + 11d = 60 , #1

" the 3rd term is -5 " ---> a+2d = -5 , #2

Solve the two equations in two unknowns using your usual method.
I would double the 2nd and subtract them

Answer 2

Is 0 know the common difference