Solve the following system by the substitution method

2x+y=4
y+2x

Present age of man is 45 years, 5 years back his age was 4 times age of his son what is present age of his son?

Which statement accurately explains whether a reflection over the y axis and a 270° counterclockwise rotation would map figure acb onto itself?

If mary had 320 toy cars and she gave her friend 50 cars and then she gave her brother 72 more cars how much toy cars would mary have left ● explain with proper details