His work should have looked like this.
2x + y = 5
x − 2y = 10
y = 5 − 2x
x − 2(5 − 2x) = 10
x − 10 + 4x = 10
5x − 10 = 10 When he added in both sides, he subtracted 10 from 10,
5x = 20 instead of adding 10 from 10 to make 20.
x = 4
2(4) + y = 5
8 + y = 5
y = -3
First set up equation for Raj, which is 10x + .5, .5 is the y-intercept because he got a head start of .5 hours
Ruth, 14x
10x + .5 = 14x
- .5 -.5
10x = 14x - .5
-14x -14x
-4x = -.5
/-4 /-4
x = .125 miles
So she will overtake him at more than .125 miles
I hop this is right, and hope this helps
Answer:
18 ounces of the 25% solution
21 ounces of the 38% solution
Step-by-step explanation:
let a be the ounces of 25% alcohol solution
let b be the ounces of 38% alcohol solution
a + b = 39
0.25a + 0.38b = 0.32(39) = 12.48
Rearrange a + b = 39:
a = 39 - b
Now we can substitute a = 39 - b into the other equation
0.25a + 0.38b = 12.48
0.25(39 - b) + 0.38b = 12.48
Simplify by distributing
9.75 - 0.25b + 0.38b = 12.48
Collect like terms
9.75 + 0.13b = 12.48
Isolate b to solve
0.13b = 2.73
b = 2.73/0.13
b = 21
Sub b = 21 into an equation to find "a"
a + b = 39
a + 21 = 39
a = 39 - 21
a = 18
Therefore we need 18 ounces of the 25% solution and 21 ounces of the 38% solution.
This looks like an addition (summation is the technical term) series. Here we need to figure out the difference between each number in the series. The difference between 6.75 and 9.25 is 2.5 (You can subtract the larger number from the smaller number to find out). So, 6.75-2.5=4.25.
So the correct answer in the blank is 4.25, and the rule is +2.5.
4/16 add all then put your total black over the number you added up