Question

Very Easy!!! Please Answer it... I need Help......
Two numbers are such that the second number is thrice the first number.When twice the first number is added to four times the second number,the sum is 420.Find the number.

Answer 1

LET THE TWO NUMBERS BE a1 and a2
then 
ATQ
a2=3a1
⇒3a1-a2=0.................(1)
2a1+4a2=420
⇒a1+2a2=210
multiply with 3 on both sides
3a1+6a2=630.............(2)
solve equation (1) and(2)
we get 
a2=90
substitute it in eq(1)
we get a1=30

Answer 2

let the two numbers be x, y
given 3x = y   -------- (1)
  2x + 4y = 420
sub x = 3y in 2x +4y = 420
  2x + 4(3x) = 420
  2x +12x = 420
 14x = 420
 x = 30
sub x = 30 in (1)
y = 3(30)
  = 90
the numbers are x = 30 and y = 90