[10.15] Terrell and Mindi are organizing a neighborhood skateboarding competition. They need to build two mini ramps. Terrell can build the ramps in 15 hours. Mindi can build the ramps in 20 hours. Which shows the equation and solution for the time it will it take Terrell and Mindi to build the ramps if they work together? Round your answer to the nearest hour, if necessary.

Question

anonymous · Answer

2 equals the quantity 2 over 15 plus 2 over 20, end quantity, times t; 9 hours 

 1 equals the quantity 2 over 15 plus 2 over 20, end quantity, times t; 4 hours 

 2 equals the quantity 15 over 2 plus 20 over 2, end quantity, times t; 4 hours 

 1 equals the quantity 15 over 2 plus 20 over 2, end quantity, times t; 9 hours

anonymous · Answer

Has anyone who taken algebra before help me?