The sum of 2 #'s is 42; 1# plus 2x other # is 57. Have answer, don't know how to write equation?

Answer 1

It's not one equation; it's an example of simultaneous equations:

x + 2y = 57
x + y = 42

I'm glad to hear you've got the answer.

Answer 2

the sum of two numbers is 42:
a + b = 42

first number + 2x second number is 57:
a + 2b = 57

(that's how you write the equations);

right now you can see that b = 15, because the difference between a+b and a+2b is 15;
a = 27 because since b = 15, 2b = 30; so 57 - 30 = 27.

OR you can solve the system of equations; here are the steps:

find the value of one variable in terms of the other one:
a + b = 42
a = 42 -b

now substitute that value for the other var, and solve:
(42 - b) + 2b = 57
42 + b = 57
b = 57 - 42
b = 15

now substitute the value of b back into the first equation to find the value of a:
a + b = 42
a + 15 = 42
a = 42 - 15
a = 27

and you're done! good luck!

Answer 3

It can be solved by one equation.
Let x = 1st number
42-x = 2nd number

x + 2(42 - x) = 57
x + 84 - 2x = 57
-x = -27
x = 27
42 - x = 15

To check:
27 + 15 = 42 and 27 + 30 = 57

Answer 4

x + y = 42; x + 2y = 57

Answer 5

Let x be one number. then 42-x is the other number.

x + 2(42-x) = 57

Answer 6

x + y = 42

x + 2y = 57
x = -2y + 57

(-2y + 57) + y = 42
-2y + 57 + y = 42
-y = -15
y = 15

x = -2(15) + 57
x = -30 + 57
x = 27

ANS : 27 and 15

Answer 7

a+b=42
a+2b=57

to solve subtract one equation from the other
2b-b=57-42
b=15

substitue the 15 for b to get a
a+15=42
a=27

(a,b)=(27,15)

Answer 8

its simultaneous equation
x+y=42
x+2y=57
(x+2y)-(x+y)=57-42
y=15
x=42-15
x=27

Answer 9

Your teacher can help