A sewing bag contains 3 gold buttons and 4 black buttons. How many buttons need to be added to the sewing bag so that there are 30% gold buttons?

3 black

Step-by-step explanation:

Currently: 7 buttons

30% gold so 70% should be black

70% = 0.7

(4+x)/(7+x) = 0.7

3+x = 0.7(7+x)

4+x = 4.9 + 0.7x

0.3x = 0.9

x = 3

94

step-by-step explanation:

average the numbers and use a variable to figure out the minimum to get a 90.

(79+94+91+92+x)/5=90

x = 94