Answer :
b=3d and b=d+4
Since b=b we can say:
3d=d+4 subtract d from both sides
2d=4 divide both sides by 2
d=2
Daniel is 2 years old. (and Ben is 6 years old)
Since b=b we can say:
3d=d+4 subtract d from both sides
2d=4 divide both sides by 2
d=2
Daniel is 2 years old. (and Ben is 6 years old)