Lixin intends to buy either gift a, which costs $10 or gift b, which costs $8, as christmas gifts for each of her parents, 2 siblings, 13 relatives and 10 friends. given that she intends to spend $230, find the number of each gift she should buyi need someone

10a + 8b = 230
a + b = (2 + 2 + 13 + 10)...a + b = 27 (this is the number of gifts to buy)

a = 27 - b

10(27 - b) + 8b = 230
270 - 10b + 8b = 230
-10b + 8b = 230 - 270
-2b = -40
b = -40/-2
b = 20 <=== she bought 20 eight dollar gifts

a = 27 - b
a = 27 - 20
a = 7 <=== she bought 7 ten dollar gifts