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

first, we define the variables:

x: number of years after 1950

f (x): amount of vinyl sold.

then, with the variables defined, we have:

68594 vinyl records were sold in 1958 > f (8) = 68594

91299 vinyl records were sold in 1961 > f (11) = 91299

38720 vinyl records were sold in 1952 > f (2) = 38720

161743 vinyl records were sold in 1967 > f (17) = 161743

read more on -

step-by-step explanation: