First, we need to determine how much Johnny makes in one day. To start, we perform 3*7=<<3*7=21>>21 dollars for the first job.
Second, we perform 2*10=<<20=20>>20 dollars for the second job.
Third, we perform 4*12= <<4*12=48>>48 dollars for the third job.
Altogether, Johnny makes 21+20+48= <<21+20+48=89>>89 dollars in a day.
We multiply this amount by the 5 days, performing 5*89= <<445=445>>445 dollars over 5 days
#### 445