Whats the mass

Magnesium carbonate, MgCO3, is used in indigestion tablets as it reacts with and neutralises stomach acids. The equation for the reaction between MgCO3 and dilute hydrochloric acid is shown below…

MgCO3(aq) + 2HCl(aq)  MgCl2(aq) + CO2(g) + H2O(l)

... and so the active constituent is the carbonate dianion, CO32-, with Mg2+ being an inert counter ion…

CO32-(aq) + 2H+ (aq)  CO2(g) + H2O(l)

Some tablets also contain aluminium hydroxide, which acts in a similar way...

Al(OH)3(aq) + 3HCl(aq)  AlCl3(aq) + 3H2O(l)

... and so the active constituent is the hydroxide anion, with Al3+ being an inert counter ion…

HO-(aq) + H+ (aq)  H2O(l)

The Gaviscon Extra Strength brand contains 0.0749 g of CO32- and 0.105 g of HO- in each tablet.

(i) What mass of Mg2+ is present in each tablet? Show your reasoning/calculation.