The three Math Idol judges have been eliminating contestants all day! The number of one-step equations and two-step equations who have been eliminated today is equal to 840! If three times the number of one-step equations minus twice the number of two-step equations is equal to 870, how many one-step equations auditioned today?

Question

hartnn · Answer

hint,let number of 1 step eq be a
and number of 2 step eq be b
so,a+b=840
3a-2b=870
can u solve these 2 equations to get a and b?

hero · Answer

If I had a nickel for every time I saw this question.

anonymous · Answer

i don't get how to solve the equations

anonymous · Answer

@hartnn how would i solve them?

hartnn · Answer

u can first find a from a+b=840
so tell me what u get as a?

anonymous · Answer

a=840-b?

hartnn · Answer

yes :)
now put it in 2nd equation
3(840-2b)-2b=870
can u get b?

anonymous · Answer

b=-206.25

hartnn · Answer

isn't it +206.25

anonymous · Answer

yes it is i found the mistake

hartnn · Answer

now just put the value of b in a+b=840 to get a

anonymous · Answer

i got 633.75 but my only choices are 330, 510, 520, 660

anonymous · Answer

i got the answer thank you