Ben - 3 * D
Ben - 3 + D
B = 3D
B = 4 + D
Since B is the same amount and these are both equivalent to B we can set them equal to each other then solve for D. Once we know D we can plug it back into one of the equations to get B.
3D = 4 + D
Get your like terms on one side (my recommendation is the smaller D value, because the larger one will lead the number to be negative, but it is up to you!)
3D - D = 4 + D - D
Simplify:
2D = 4
Divide by 2 on both sides.
2D/2 = 4/2
Simplify!
D = 4/2 = 2
Plug that back into one of the equations.
B = 3*D
B = 3*(2)
Ben is, 6 years old! .
