[求助]ASK HELP ABOUT ONE PREP MATH Q!!

shlingw

If  each term in the sum a1+a2+...an is either 7 or 77 and the sum equals 350.
which of the following could be equal to n?

What is the meaning of this Question???

Whitney

Question: is if 7*X+77*Y=350 and X+Y=  n  => what is the possible number for n?

=>  7*X+77*Y=350  => X+11*Y = 50 => X+Y = 50 -10*Y => n = 50 -10 Y

since Y= 0, 1,2,3,4; => n= 50, 40, 30, 20, 10