Grade 7 Algebraic Expressions Worksheets Grade 7 Maths Algebraic Expressions Long Answer Type Questions. 1. From the sum of 5y 2 + 7yz, -5y 2 - yz - z 2 and 4yz + 3z 2, subtract the sum of 5y 2 - 3z 2 and 8y 2 + yz - 6z 2. 2. In an isosceles triangle, the base angles are equal, the vertex angle is twice either the base angle.