Answer:
Paul created 10 three minutes songs and 12 four minutes songs.
Explanation:
The song he created on his CD is either 3 minutes long or 4 minutes long.
His CD has 22 songs and is 78 minutes. The number of 3 minutes and 4 minutes song can be calculated below.
Let
a = number of 3 minutes song
b = number of 4 minutes song
number of song = 22
a + b = 22............(i)
3a + 4b = 78.........(ii)
Make a subject of the formula in equation (i)
a = 22 - b
Insert the value of a in equation (ii)
3(22 - b) + 4b = 78
66 - 3b + 4b = 78
b = 78 - 66
b = 12
insert the value of b in equation (i)
a + b = 22
a + 12 = 22
a = 22 - 12
a = 10
Paul created 10 three minutes songs and 12 four minutes songs.