Common difference can be found by taking away first term from the second term.

Can we use the inverse operation here?

Can we solve the linear equation for a and d?

Can we find the common difference?

Find its first term and the common difference by solving the linear equation.

Put the value of only a and d, and get your answer in terms of n.

Can we put the values in the formula to get our answer?

Can we use the sum of terms formula from A.P here?

Think of the largest number which is divisible by 7, and less than 60.

Can we first find the number of terms , using the sum formula?