## Geometry: Common Core (15th Edition)

I) $b=2a-5$
To solve an expression for a given variable, isolate that variable on one side of the expression. $10a-5b=25$ Use the addition property of equality to subtract 10a from each side. $10a-5b-10a=25-10a$ Combine like terms. $-5b=25-10a$ Use the multiplication property of equality to divide both sides by -5. $-5b\div-5=(25-10a)\div-5$ Divide. Use the distributive property to divide the right side. $b=-5+2a$ Restate using the commutative property. $b=2a-5$