Answer:
The solution for problem a is cross multiplication
5×500=2500 and 15×x=15× so 15×=2500
divide both sides by the coefficient 15. 15x ÷15=×
divide 2500 by 15=500
x=500/3= approximately 166.7
Solution for b:
This one's easy!!
10/20=x/500
cross multiply
10×500=5000
20×X=20x
now we have the equation. 20x=5000
stay with me. I hope this makes sense ^_^
divide both sides by the coefficient 20
20x÷20=x
5000÷20=250
x=250
a is true
i hope this helps ;)