MEDAL
Frankie can build a speaker box in 120 minutes. Tisha can build a speaker box 40 minutes faster. If they work together, how many minutes does it take them to build the speaker box?

Question

anonymous · Answer

answer choices 
240
80
48 
40

anonymous · Answer

frankie can do it in 120 minutes, tisha can do it in 80 minutes, together the can do it in $t$ minutes

$$\frac{ 1 }{ 120 }+\frac{ 1 }{ 80 }=\frac{ 1 }{ t }$$
multiply by the lcd of 240t
$$2t+3t=240$$

anonymous · Answer

80

anonymous · Answer

48 sorry