One number is seven more than three times another number. If the sum of the numbers is 15, find the numbers.

2 and 13

Step-by-step explanation:

We can use systems of equations here to find both the numbers. Let's assume one of the numbers is and the other is .

We know that these numbers add up to 15, so .

We also know that one of these numbers is 7 more than 3 times the other, so .

We can now substitute the equation into .

Combine like terms:

Subtract 7 from both sides:

Divide both sides by 4:

.

Now that we know the value of , we can substitute it inside an equation to find . Let's substitute it inside .

So the two numbers are 2 and 13.

Hope this helped!

x = -3

y = -18

step-by-step explanation:

to solve by substitution, substitute one variable and solve for the other. then substitute again to find the remaining variable.

x-1/3(3x-9) = -3 since y=3x-9 substittute y.

x-1/3(3x-9)=-3

x + x +3 = -3

2x+3=-3

2x+3-3= -3-3

2x=-6

x=-3

substitute again into y=3x-9

y=3(-3)-9

y=-9-9

y=-18

b) 1/3 * 1/5

step-by-step explanation:

each smallest part is 1/15 since the written one is 1/5 and it's divided by 3 equal parts. (1/5 )/3 = 1/15 = 1/3 * 1/5