The sum of eli's age and cecil's age is 15. In 25 years, their combined age will be a total of twice eli's age and 4 times cecil's. How old is cecil?

Step-by-step explanation:

The first equation is pretty easy to write.

The sum of Eli and Cecil's age is 60.

Let x = Eli's age

Let y = Cecil's age

Sum means add, so:

x + y = 60

The second equation is a little tricker.

Six years ago, Eli was three times as old as Cecil.

Six years ago means we have to subtract 6

Think:

Eli (six years ago) = 3 times cecil's age (six years ago)

x - 6 = 3(y-6)

Now, let's use the distributive property.

x - 6 = 3y - 18

Next we'll get the variables on one side and the constants on the other in order to write the equation in standard form.

x - 3y - 6 = 3y -3y - 18 Subtract 3y

x - 3y - 6 = -18

x - 3y - 6 + 6 = -18 + 6 Add 6

x - 3y = -12

Now we have two equation in standard form:

x + y = 60

x - 3y = -12

You can solve easily by using substitution or linear combinations.

I will use the linear combinations method.

Step 1: Create 1 set of opposite terms.

x + y = 60

-1 ( x - 3y) = -12(-1)

x + y = 60

-x + 3y = 12

Step 2: Add

x + y = 60

-x + 3y =12

4y = 72

Step 3: Solve for y

4y/4 = 72/4

y = 18

Cecil's age is 18

Step 4: Substitute to find Eli's age.

x + y = 60

x + 18 = 60

x+18 - 18 = 60 -18

x = 42

Eli's age is 42.

Check:

42 + 18 = 60

Six years ago:

Eli was 36

Cecil was 12

Eli was 3 times as old as Cecil 6 years ago.

12 * 3 = 36

Hope this helps

step-by-step explanation:

you can add the two numbers and divide the result by 2. or you can find the gap between the two numbers and add half of this to the smaller number.

answer is because 4×10=40

and 98×4= is 392

40,392