Without considering the sign:
It's sigma(1 to 5, 5k+2)
Since the first item is minus, you simply add (-1)^k
So it's sigma(1 to 5, (-1)^k * (5k+2)
I choose A
Substitution is a method of finding x or y value by taking,
——-
1st full equation in name of x and substituting to get the value.
Hope helped
X = Ishaan
y = Christopher
3y = x
x = y + 14 Put the first equation into the second.
3y = y + 14
2y = 14
y = 7
Christopher is 7
Ishaan is 21
D is most likely right. Basically, I would turn them into decimals and divide using a graphing calculator.