Answer :
[tex] \: \: \: \: \: \: [/tex]
[tex] = \: \: \: \: r = 5[/tex]
Step-by-step explanation:
[tex]7 + 4(r + 3) = 9r - 6[/tex]
- distribute 4 through the parentheses
[tex]7 + 4r + 12 = 9r - 6[/tex]
- add numbers
[tex]19 + 4r = 9r - 6[/tex]
- move the variable to the left hand side and change its sign
[tex]19 + 9r = - 6[/tex]
- move the constant to the right hand side and change its sign
[tex]4r - 9 = - 6 - 19[/tex]
- collect like terms
[tex] - 5r = - 6 - 19[/tex]
- calculate the difference
[tex] - 5r = - 25[/tex]
- divide both sides of the equation by -5
[tex] = \: \: \: \: r = 5[/tex]