The first step to do is to calculate first the total household waste generate for the two years. That is:
total waste generated = 23,400,000 tons + 48,100,000 tons
total waste generated = 71,500,000 tons
Now, to write either a very big number or a very small number in a form of scientific notation simply means to write it in a decimal form such as: 12.5 * 10^10
Now to write 71,500,000 in scientific notation, the decimal form is 7.15, however we still need to find out the * 10^n factor. The value of n depends on the number of places the decimal point was moved. If the movement was from right to left, the value of n is positive and if the movement was from right to left, the value of n is negative. Since the decimal point was moved by 7 places, hence the complete scientific notation is:
7.15 * 10^7 tons