exam Maths Puzzle Numerical Ability

I know how to do these I really just need to be refreshed the question I am having trouble with is .5n(n+1)to the second power

Read Solution (Total 0)

exam Other Question

Please help. I do not even know what to call this.
Solve each of the following systems by addition. If a unique solution does not exist, state whether the system is inconsistent or dependent.

2x+3y=1
5x+3y=16 I am trying to solve this problem

8a^2-18ay+7y^2