Given the point (5, 6) and the slope of 5, find y when x = 21.
86
90
105
111

Which values for a and b will create infinitely many solutions for this system of equations? ax-y=8 2x+y=b

Prove that the sum of two consecutive exponents of the number 5 is divisible by 30.if two consecutive exponents are 5n and 5n + 1, then their sum can be written as 30.

David is spreading mulch on a triangular area of his flower bed. the coordinates of the vertices of the area are (1, 3), (9, 3), and (4, 6). what is the area of the triangle if each square has an area of 3 square feet?