The treadmill display indicated that Joanna had completed 30% of her workout with 35 minutes remaining. How much time had she already spent on the treadmill?

Since when is "college" a School Subject?

.7X = 35

X = 50
Her workout time is 50 minutes, but she has spent 30% of that, or
.3(50)minutes, or 15 minutes.

where did u get 7 from?

100% - 30% = 70%

1.00 - 0.3 = 0.7

To determine how much time Joanna had already spent on the treadmill, we can use a simple proportion based on the given information.

First, let's represent the total time of Joanna's workout as "x" minutes.

According to the treadmill display, Joanna had completed 30% of her workout with 35 minutes remaining. This means she had yet to complete 70% of her workout.

We can set up the following proportion:

(30 / 100) = (x / 70)

To solve this proportion, we cross-multiply:

100 * x = 30 * 70

Divide both sides by 100:

x = (30 * 70) / 100

Simplifying this equation:

x = 21 * 7

x = 147

Therefore, Joanna had already spent 147 minutes on the treadmill.