On which one do you need help with?
A collection of nickels and dimes is worth $4.40. There are 53 coins in all. How many nickels are there?
Nickel is a US coin worth 5 cents or 0.05.
Dime is a US coin worth 10 cents or 0.10
n + d = 53
0.05n + 0.10d = 4.40
n = 53 - d
0.05(53 - d) + 0.10d = 4.40
2.65 - 0.05d + 0.10d = 4.40
0.05d = 4.40 - 2.65
0.05d = 1.75
d = 1.75 / 0.05
d = 35
n = 53 - d
n = 53 - 35
n = 18
There are 18 nickels and 35 dimes.
0.05n + 0.10d = 4.40
0.05(18) + 0.10(35) = 4.40
0.90 + 3.5 = 4.40
4.40 = 4.40
The last one is not necessarily true
Step 1: Set up the proportion
4/12 = 10/x
Step 2: Cross multiply to get
120 = 4x
Step 3: Divide all by 4 to get
30 = x
Answer: So in total, 10 students would spend $30 on lunch!
