human
A pen costs as much as a pencil and eraser combined. A pencil costs $1.20 and an eraser costs $0.30. How much will 8 pens cost?
assistant
How much does a pen cost? ** A pen costs $1.20 + $0.30 = $<<1.20+0.30=1.50>>1.50.
How much will 8 pens cost? ** So, 8 pens cost $1.50 x 8 = $<<8*1.5=12>>12.
#### 12