Substitution is where we first Isolate one of the unknowns, express it in terms of the other unknown, and replace the isolated unknown with the other unknown in another equation. So that each time we only need to deal with one unknown. I think you'll get a better idea here:
First name these 2 equations with 1 and 2.
4x + 5y = 7 (1)
y = 3x + 9 (2)
Since y is already isolated in (2), so we can skip the isolation step and continue to substitute.
Substitute (2) into (1).
4x + 5(3x+9) = 7
Expand.
4x + 15x + 45 = 7
Group.
19x + 45 = 7
Shift +45 to the other side and turn it into -45.
19x = 7 - 45
19x = -38
Shift x19 to the other side, turn it into /19.
X = - 38/19
X = - 2
Now we solved x already, we can just substitute x= - 2 back to equation (2).
y = 3(-2) + 9
y = - 6 + 9
y = 3
So, the answers are
x = - 2
y = 3
Answer:
Total Bill = 4006 dollars
Step-by-step explanation:
A cell phone company charges a flat fee of 20 dollars plus 3 cents a call.
If there was a total of 200 calls for the month, the total charge by the cell phone company will be.
Let me convert all to cent first
100 cent = 1 dollar
20 dollar =20 *100
29 dollar = 2000 cent
Charge by the company for a call is 2003 cent
Let me put down the equation.
1 call = 2003 cent
200 calls =( 200 calls* 2003cent)/1 call
200 calls = 200 * 2003cent
200 calls = 400600 cent
Let's convert back to dollar
100 cent = 1 dollar
400600 cent = 400600/100
400600 cent = 4006 dollars
Answer:
lol
Step-by-step explanation:
im not even sure try using google
