Barry has 18 more marbles than heidi. if barry has 92 marbles, write and solve an equation to determine the number of marbles heidi has.

N = Heidi's marbles

92 - n = 18 (Barry's 92 marbles - whatever Heidi has = 18 marbles difference)

92 - n + n = 18 + n (I added n to each side)

92 = 18+n

92 - 18 = 18-18 + n (I subtracted 18 from both sides)

74 = n Heidi has 74 marbles