Count One Quantity Two Ways and Equate
A word problem becomes an equation when the same quantity -- children, years, buyers -- can be expressed twice in terms of the unknown. Choose the unknown, write both expressions, set them equal. The elementary sum-and-difference problems are an earlier, narrower strategy worth recalling; here the two expressions can be anything the story gives.
grade 7 Expressions Convert to AlgebraOrganize Information in More Ways
Progression (3)
g7 1. Count the children two ways and equate ExpressionsRatios
g7 2. Express years married two ways, then equate Expressions
g7 3. Split buyers into only-coffee, only-cake, both RatiosExpressions