Given:
We're given the steps a student took to solve the simple interest formula.
To find:
The algebraic error in student's work.
Step-by-step solution:
Let us first solve the equation and then we will spot the error in the solution:
A = P(1 + rt)
A = p + prt
A - p = prt
A - p / pt = r
Upon comparing both solutions, we can clearly see that the student made a mistake in the second step in the multiplication process.
The student should write A = p + prt in the second step in place of
A = p + rt, because p is multiplied with the whole bracket.