To solve this question, follow the steps below.
Step 01: Write the numbers to have the same powers.
To do it, choose one number to transform.
Let's choose the number with the greaters power (10⁻³).
To write it with the power -4, multiply 7.94 by 10:
![\begin{gathered} 7.94*10^(-3)=7.94\operatorname{*}10*10^(-4) \\ =79.4\operatorname{*}10^(-4) \end{gathered}]()
Step 02: Solve the subtraction.
To solve the subtraction, subtract the decimals.
![\begin{gathered} 79.4\operatorname{*}10^(-4)-6.69\operatorname{*}10^(-4) \\ =(79.4-6.69)\operatorname{*}10^(-4) \\ =72.71\operatorname{*}10^(-4) \end{gathered}]()
Step 03: Rewrite the number in scientific notation.
For a number in scientic notation a x 10ᵇ, 1 ≤ |a| < 10.
Then, divide 72.71 by 10 and multiply the exponent part by 10.
Answer:
