Question

Ted needs an average of at least 70 on his three history test he has scored already 85 and 60 on two test what is the minimum grade ted need on his third test?

Answer 1

so average=(total of scores)/(number of tests)
needs at least average of 70
at least is represented as greater than or equal to or the sign (>)
70>(total)/(number oftests)

since we have 3 tests, we have to have 3 scores so
70>(x+y+z)/3
he scored 85 and 60
70>(x+85+60)/3 (doesn't matter which to subsitute)
70>(x+145)/3
multiply obht sides by 3
210>x+145
subtract 145 from both sides
65>x
he needs to get at leas 65 on his third test