Final answer:
The value of -4(7x+5y) when 7x+5y equals -9 is 36, as the operation simplifies due to the distributive property of multiplication over addition.
Step-by-step explanation:
If 7x+5y=-9 is a true equation, multiplying both sides by -4 will give us the value of -4(7x+5y). Since multiplication is distributive over addition, -4 multiplied by each term inside the parentheses yields -4(7x) + (-4)(5y), which simplifies to -28x - 20y. However, because we know 7x+5y equals -9 from the original equation, the expression -4(7x + 5y) simplifies to -4(-9), which equals +36. Therefore, the value of -4(7x+5y) is 36.