A metalsmith is mixing two molten metals, each containing different percentages of silver. The table shows the amount of each molten metal used. Which two expressions are both equivalent to t, the total number of grams of silver in the mixture?
A: (15)(0.75) and 0.7(15 – x) + 0.9x
B: (15)(0.75) and 0.7(15 – x)(0.9x)
C: 15 + 0.75 and 0.7(15 – x) + 0.9x
D: 15 + 0.75 and 0.7(15 – x)(0.9x)