# Tutor profile: Olivia D.

## Questions

### Subject: Basic Chemistry

Balance the following equation: FeCl3 + MgO ---> Fe2O3 + MgCl2

1) Balance the Cl (note that 2 x 3 = 3 x 2): 2FeCl3 + MgO ---> Fe2O3 + 3MgCl2 The Fe also gets balanced in this step. 2) Pick either the O or the Mg to balance next: 2FeCl3 + 3MgO ---> Fe2O3 + 3MgCl2 The other element (Mg or O, depending on which one you picked) also gets balanced in this step.

### Subject: Biology

What are the conditions for which the Hardy-Weinberg equation can apply to a population?

The following conditions must occur in order to apply the Hardy-Weinberg equation 1. Large population 2. Mate randomly 3. Experience no genetic mutations 4. No immigration or emigration must occur 5. No natural selection can occur

### Subject: Algebra

Solve using substitution. x = 8 -4x + 5y = 18

Use substitution to solve the system of equations: x = 8 -4x + 5y = 18 Step 1: Isolate a variable. The variable x is already isolated in the first equation. Step 2: Plug the result of step 1 into the other equation and solve for one variable. Plug x = 8 into the other equation, -4x + 5y = 18 and find the value of y -4x + 5y = 18 -4(8) + 5y = 18 Plug in x = 8 -32 + 5y = 18 Multiply 5y = 50 Add 32 to both sides y = 10 Divide both sides by 5 Step 3: Plug the result of Step 2 into one of the original equations and solve for the other variable. The first equation already shows that x = 8, so it is not necessary to plug in and solve for x. Step 4: State the solution. Since x = 8 and y = 10, the solution is (8, 10).

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