2s-4 +s = 20 solve for s

+4 +4

——————-

3s = 24

— —

3 3

s = 8 now solve for r in the first equation

r = 2(8)-4 = 16 – 4 = 12

Ricardo is 12 and his sister is 8

by the way, always show your work

2x-4=ricardo’s sister’s age

20=sum of their age

equation:

(2x-4)+ x=20

3x-4=20

3x=20+4

x=24/3

x=8

To check the answer:

2x-4 + x = 20

[2(8)-4} + 8=20

[16-4] +8 = 20

12 + 8 = 20

20=20

therefore: his sister is 12 which is twice his age (8) less 4

Ricardo is 8

hope this could help you! 🙂

His sister is 8

12 + 8 = 20

Math: 8 (sister) x 2 = 16 – 4 = 12 (Ricardo)

s +2s -4 =20

3s = 24

s = 8

so sister is 8 and ricardo is 12

So her sister=20-x

x=2(20-x)-4

or x=40-2x-4

or 3x=36

or x=12=Ricardo

His birthday is tomorrow!;-)