Suppose that the world's current oil reserves is \( R=2000 \) billion barrels. If, on average, the total reserves is decreasing by 25 billion barrels of oil each year, answer the following: A.) Give a linear equation for the total remaining oil reserves, \( R \), in billions of barrels, in terms of \( t \), the number of years since now. (Be sure to use the correct variable and Preview before you submit.) \( R=\square \) B.) 9 years from now, the total oil reserves will be C.) If no other oil is deposited into the reserves, the world's oil reserves will be completely depleted (all used up) approximately (Round your answer to two decimal places.)

A.) The linear equation for the total remaining oil reserves, \( R \), in billions of barrels, in terms of \( t \) (the number of years since now) can be expressed as: \[ R = 2000 - 25t \] B.) To find the total oil reserves 9 years from now, substitute \( t = 9 \) into the equation: \[ R = 2000 - 25(9) = 2000 - 225 = 1775 \] So, 9 years from now, the total oil reserves will be 1775 billion barrels. C.) To determine when the reserves will be completely depleted, we set \( R = 0 \): \[ 0 = 2000 - 25t \] Solving for \( t \): \[ 25t = 2000 \] \[ t = \frac{2000}{25} = 80 \] Thus, the world's oil reserves will be completely depleted in approximately 80 years from now.