Josh works 8 hours/day * 5 days/week * 4 weeks/month = <<8*5*4=160>>160 hours a month.
He earns 160 hours/month * $9/month = $<<160*9=1440>>1440 per month.
Carl works less because he is an intern: 6 hours/day * 5 days/week * 4 weeks/month = <<6*5*4=120>>120 hours per month.
Carl earns 120 hours * $4.5/hour = $<<120*4.5=540>>540 per month.
The company pays for the 2 together: $1440 + $540 = $<<1440+540=1980>>1980.
#### 1980