What is the equation?
2006-12-07 12:21:23 · 8 answers · asked by tgifrichard 1 in Science & Mathematics ➔ Mathematics
let the first multiple of 15 be 15x. Then the next multiple would be 15x+15, the third would be 15x+30, and the fourth would be 15x+45. Their sum (and the equation) would be 60x+90 = 390. then x=5. the largest of the 4 multiples is 15x+45=15*5+45=120. Hope this helps!
2006-12-07 12:22:37 · answer #1 · answered by need help! 3 · 0⤊ 0⤋
15a+15(a+1)+15(a+2)+15(a+3)=390, where 15(a+3) is the largest multiple.
Just because I'm feeling nice, I'll also solve the equation.
15a+15a+15+15a+30+15a+45=390
60a+90=390
60a=300
a=5
15a=75, 15(a+1)=90, 15(a+2)=105, 15(a+3)=120, so 120 is the largest.
2006-12-07 12:59:12 · answer #2 · answered by dennismeng90 6 · 0⤊ 0⤋
75 + 90+ 105+ 120 = 390
120 is the largest
2006-12-07 12:26:00 · answer #3 · answered by Anonymous · 0⤊ 0⤋
15x + 15(x+1) + 15(x+2) + 15(x+3) = 390
15x + 15x + 15 + 15x + 30 + 15x + 45 = 390
60 x + 90 = 390
60x = 300
x = 5
The largest multiple of 15 is 15(5+3) = 120.
2006-12-07 12:27:06 · answer #4 · answered by smaatgg 2 · 1⤊ 0⤋
75+90+105+120=390
120 is the largest
2006-12-07 12:24:56 · answer #5 · answered by BRIAN M 1 · 0⤊ 0⤋
15n + 15 (n+1) + 15 (n+2) + 15 (n+3) = 390
60 n + 90 = 390
n = 5
the numbers are 75, 90, 105, 120
2006-12-07 12:24:10 · answer #6 · answered by ♪ ♫ ☮ NYbron ☮ ♪ ♫ 6 · 0⤊ 0⤋
75+90+105+120
I divided 390 by 4, which was 97.5. So two of the numbers had to be below 97.5, and two had to be above 97.5. (Because 97.5 was the average of all 4).
2006-12-07 12:25:29 · answer #7 · answered by Stephanie 2 · 0⤊ 0⤋
n is the largest
15 (n + n - 1 + n - 2 + n - 3) = 390
4n - 6 = 26
4n = 32
n = 8
2006-12-07 12:36:40 · answer #8 · answered by Imoet 2 · 0⤊ 1⤋