Answer: He would pay 45% of the original price.
Step-by-step explanation:
Since we have given that
Let the original price of item be 'x'
Rate mark down by 25%
Amount of marked down would be

Amount after marked down becomes

Additional clearance items by 40% off
Amount of additional off is given by

After additional off, the amount becomes,

Hence, he would pay 45% of the original price.
The time taken for radio signal to the earth's surface we shall proceed as follows;
time=(distance)/(speed)
Distance=7.5×10^6 meters
speed=3×10^8 meters/second
therefore:
Time=(7.5×10^6)/(3×10^8)=0.025 seconds
We conclude that it will take the signal 0.025 seconds to reach the surface of the earth.
Answer:25
Step-by-step explanation: