What number belongs in the box to make the equation true

X+ y = k 2x + 3y = k + 1 the point of intersection of the lines has an x-coordinate of a.2k + 1 b.-2k + 1 c.2k - 1

Noor brought 21 sheets of stickers. she gave 1/3 of a sheet to each of the 45 students at recess. she wants to give teachers 1 1/2 sheets each.

Acollection of coins has value of 64 cents. there are two more nickels than dimes and three times as many pennies as dimes in this collection. how many of each kind of coin are in the collection?