Determine whether the function represents exponential growth or exponential decay. Identify the percent rate of change. y = 4(0.8)
The function represents exponential decay
The rate of change is_%

Jada has a meal in a restaurant she adds up the prices listed on the menu for everything they ordered and gets a subtotal of $42.00. when the check comes, it says they also need to pay $3.99 in sales tax. what percentage of the subtotal is the sales tax

I’m still confused on how to work the percentages

Prove sin2a + cos2a - 1 / sin2a + cos2a + 1 = 1 - tana / 1 + cota