Allright to find this you have to put the equation into order again. The equation of a line is y=mx+c. M= Gradient. C = Y intercept. After you put it in order you just have to read it. If you need the answers comment ill find them...
Total number of volunteer students for a committee = 7
Number of committee = 5
Number of ways of selecting the committee from the 7 volunteers = 7C5 = 7!/(5!*2!) = 21 ways.
There are 21 ways in which the 5-committee member can be selected from the 7 volunteers.
There isn't enough info to determine that, I believe. You would need an equation that would allow me to determine the minimum output for an A.