Lena has 2 boxes of buttons a and b. in total are 1.200 buttons .she move 360 buttons from box a to b. there are now 3 times as many buttons in box b than box a. homany buttons were in box a at the start?

660

Step-by-step explanation:

Let  A = number of buttons in Box A

and B = number of buttons in Box B

We have two conditions:

(1)            A + B = 1200

(2)       B + 360 = 3(A – 360)     Remove parentheses

          B + 360 = 3A - 1080      Subtract 360 from each side

(3)                 B = 3A - 1440       Substitute (3) into (1)

A + 3A - 1440 = 1200               Combine like terms

      4A - 1440 = 1200               Add 1440 to each side

                4A  = 2640               Divide each side by 4

                   A = 660

80%

step-by-step explanation: