Sagot :
[tex]RS+ST=RT\\\\
RS=8y+4\\
RT=15y-9\\
ST=4y+8\\\\
8y+4+4y+8=15y-9\\
12y+12=15y-9\ \ \ |Subtract\\
12y=15y-9-12\\
12y=15y-21\ \ \ | Subtract\ 15y\\
12y-15y=-21\\
-3y=-21 \ \ |Divide\ by\ (-3)\\
y=7\\\\
RS=8y+4=8*7+4=56+4=60\\
RT=15y-9=15*7-9=105-9=96\\
ST=4y+8=4*7+8=28+8=36 [/tex]
First write your equation to solve for y. You know RS plus ST equals RT.
8y + 4 + 4y + 8 = 15y - 9
Next combine like terms on the left side of the equal sign.
8y + 4y + 4 + 8 = 15y - 9
Then add the like terms.
12y + 12 = 15y - 9
Simplify using algebra. Subtract 12y from both sides.
12y + 12 = 15y - 9
-12y -12y
12 = 3y - 9
Now add 9 to both sides.
12 = 3y - 9
+9 +9
21 = 3y
Divide both sides by 3. Now you have your y value.
21 = 3y
/3 /3
7 = y
Now that you have the y value (7), just plug it into the equations for each side.
RS:
8y + 4
8 * 7 +4
56 + 4
60
RS = 60
ST:
4y + 8
4 * 7 +8
28 + 8
29
ST = 36
RT:
15y - 9
15 * 7 - 9
105 - 9
96
RT = 96
We know these are correct because RS + ST should equal RT. Does 60 + 36 = 96? Yes.
Hope this was of help!
8y + 4 + 4y + 8 = 15y - 9
Next combine like terms on the left side of the equal sign.
8y + 4y + 4 + 8 = 15y - 9
Then add the like terms.
12y + 12 = 15y - 9
Simplify using algebra. Subtract 12y from both sides.
12y + 12 = 15y - 9
-12y -12y
12 = 3y - 9
Now add 9 to both sides.
12 = 3y - 9
+9 +9
21 = 3y
Divide both sides by 3. Now you have your y value.
21 = 3y
/3 /3
7 = y
Now that you have the y value (7), just plug it into the equations for each side.
RS:
8y + 4
8 * 7 +4
56 + 4
60
RS = 60
ST:
4y + 8
4 * 7 +8
28 + 8
29
ST = 36
RT:
15y - 9
15 * 7 - 9
105 - 9
96
RT = 96
We know these are correct because RS + ST should equal RT. Does 60 + 36 = 96? Yes.
Hope this was of help!